Fukumoto and Morita 2000
An analytical study was carried out on panel zone behavior of steel beam-to-square CFT column connections. The authors proposed a nonlinear stress-strain model to estimate the elasto-plastic response of the panel zone. The analytical findings were compared with the experimental results.
Analytical Study
For modeling of the panel zone, the load-deformation relations of the steel tube and concrete were superimposed. The steel tube had a tri-linear stress-strain relation defined by a yield point, a plastic stiffness degradation point, and an ultimate strength point. The concrete stress strain relation was also tri-linear and it consisted of a cracking strength point, an ultimate strength point, and strain point at which the ultimate strength is retained. An arch mechanism in the connection was introduced to calculate the ultimate strength of the concrete. The arch mechanism had a main arch compression strut and a confining arch compression strut. The ultimate strength of the concrete was obtained by summing the ultimate the strengths of the two compression struts.
The proposed analytical model for the joint panel was applied to a wide range of specimens from the literature. The specimens included welded connections having either internal or external diaphragms. Good correlation was obtained with the experimental results up to a shear deformation level of 0.04 radians. Beyond that level, the analytical curves remained below the experimental ones.
Reference
Fukumoto, T. and Morita K. (2000). “Elasto Plastic Behavior of Steel Beam to Square Concrete Filled Steel Tube(CFT) Column Connections,” Composite and Hybrid Structures, Proceedings of the Sixth ASCCS International Conference on Steel-Concrete Composite Structures, Xiao, Y. and Mahin, S. A. (eds.), Los Angeles, California, March 22-24, 2000, Association for International Cooperation and Research in Steel-Concrete Composite Structures, Los Angeles, California, pp. 565-572.